Biofilms of K. pneumoniae, including CRKP, exhibit marked tolerance to standard concentrations of PAA used in endoscope reprocessing. These data suggest that routinely used disinfection conditions may not be sufficient when biofilm formation is likely. Disinfection parameters in areas at high risk of biofilm contamination, e.g., endoscope reprocessing, and in the context of CRKP outbreaks should be reviewed and adjusted if necessary.